Studies are proposed which will employ lung slices, suspended alveolar macrophages, and type II alveolar cells (both freshly isolated and in short-term culture) to investigate aspects of lipid metabolism in the lung alveolus. Experiments will focus on (1) synthesis of fatty acids and acyl exchange between neutral lipids and surface active phospholipids; (2) synthesis, exchange, and secretion of cholesterol by type II cells; and (3) the metabolic basis for intra-alveolar accumulation of saturated phospholipids induced by the inhibitor of cholesterol synthesis, AY-9944.